The purpose of this multicenter study is to determine the prevalence of soy allergy in children less than 3 years of age with IgE-mediated cow's milk allergy (CMA). All children with milk challenge-confirmed CMA are placed on soy formula and monitored for at least one year for development of allergic symptoms. Suspected symptoms are investigated with blinded challenges to soy. Patients are being enrolled at 4 centers and no results are yet available.